Thermostat control cam for automatic flatirons



F. E. FINLAYSON 2,602,352

July 8, 1952 THERMOSTAT CONTROL CAM FOR AUTOMATIC FLATIRONS OriginalFiled June 15, 1946 lnvehbor: Frank EFinlayson,

I I by /M H i s Attorne.

Patented July 8, 1952 ES PT OFFICE v THERMOSTAT CONTROL CAM FORAUTOMATIC FLATIRONS Frank- E/Finlayson, Ontario, Calif; assignor toGeneral Electric New York Original application 676,909. Divided andCompany, a corporation 1950, Serial No. 165,215

This invention relates to flatirons, more particularly to electricallyheated flatirons, and it has for its object the provision of improvedmeans for controlling the flatiron temperature.

More particularly, this invention contemplates improvements inthermostatic means for controlling the iron heating means to holdpreselected soleplate temperatures, and it contemplates an improvedorganization of elements resulting in an inexpensive, reliable andeasily adjustable thermal control device; more especially one whichincludes a manually operable ad 'justable control element located at thefront upper part of the iron. g V v The present application is adivision of my earlier application, Serial No. 676,909, filed June 15,1946, now Patent No. 2,543,736, and assigned to the same assignee as thepresent application. The control cam for the thermostat, and itsmounting in the fiatiron, will be claimed here. For a more completeunderstanding of this invention, reference should be had to theaccompanying drawings in which Fig. 1 is a vertical side elevation of anelectrically heated flatiron embodying this invention, parts shown insection so as to illustrate certain structural details; Fig. 2 is a planview of certain of the elements shown in Fig. 1-; and Figs. 3 and l areelevations of the cam elements used in the thermal control, parts beingbroken away for clarity. 7

Referring to the drawings,-this invention has been shown in one form asapplied to an electrically heated flatiron comprising a soleplate ll)havingat itsbotom the usual pressing surface I l, which plate will bemade of any suitable metal,v

such as aluminum, and which preferably will be cast from the metal. Thesoleplate has the usual shapeprovided with a point l2 end, and having aslightly rounded heel edge l2a opposite the point. The soleplate isheated by means of an electrical heating element which preferably is ofthe sheathed type, and comprises a helical electrical resistanceconductor [3 (Fig. 1) mounted within a tubular bedded in and held inspaced relation to the sheath by a compacted mass [5 of electricallyinsulating and heat conducting material, such as compacted granularmagnesium oxide. Connected to opposite ends of the resistance conductorl3 and projecting from the twoends of the sheath are terminals l6 andI1. The'heating element has roughly the shape of a U (Fig. 2), and it isarranged in the soleplate In with its bight located at the pointed end12 of the iron and its terminals l6 and H at the heel end of the at theforward sheath l4 and im-- 4 Claims. (01. 74-5 67) June 15, 1946, SerialNo. this application May 31,

lIOll. within the body of the soleplate, as shown, the metal of theplate cast about the upper part of the element forming an upright ribHi.

The soleplate is covered by means of a shell l9, which has its loweredge resting upon a ledge 20 formed on the opposite sides of thesoleplate, and which is secured by means of a pair oftransversely-spaced screws 29a tapped into upright bosses 201) formed onthe soleplate. The shell slopes downwardly from its forward end to therear, and at the rear it is provided with a downturned wall 21 which isspaced to the rear of the soleplate heel edge l2a, as shown, and whichconstitutes a heel rest for the iron. The space between the heel edgel2a and the down-turned wall 2! is closed by means of a plate 22attached to the soleplate by means of screws 23 and projecting outwardlytherefrom to engage the inner surface of the wall 2|.

Mounted on the top of the shell is a handle 24 formed of any suitablematerial, but preferably it will be molded of an electrically insulatingmaterial such as a phenolic condensation product. The handle is providedwith a hand-grasping portion 25 running from the front to the rear ofthe iron, and with a forward skirt section26 and arear upright section21 formed integrally with the handgrasping portion. The rear section 21constitutes a support for the rear end of the hand-grasping portion 25and is secured to the rear end of the shell by a pair of screws 28spaced apart transversely of the shell (only one being shown in Fig.1)'; preferably, and as shown, the screws will pass through uprightbosses 29 (Fig. 1) formed upwardly from the material of the shell andwhich function to space the rear handle support 21 from the shell, andthereby thermally insulate it from the shell. s

The forward end of the hand-grasping portion 25 is supported by means ofa metallic upright bracket 30 having roughly the shape of a Z. Thisbracket, as shown, extends upwardly into acavity 26a provided by theskirt 26. The lower arm 30a of this bracket rests upon a baffle plate 3|which is mounted on the top wall of the shell l9. It is secured to thebaifie plate by means of a rivet 32 and is prevented from moving aboutthe axis of the rivet by means of a down-turned section 33 which isreceived in an aperture provided for it in the baflie plate. The baflieplate 3!, in turn, is secured to the top wall of the shell by means of apair of transversely spaced rivets 34 (only one shown) positioned onopposite sides of rivet 32, and extending through downwardly extendingPreferably, the heating element is cast 3 bosses 35a formed in thebaflle and spacing it from the shell. The baffle is held inspacedrelation with the shell by means of the down-turned bosses 34a aroundthe rivets and which are formed from the material of which the bafiie ismade. The upper arm 35 of the z shaped bracket 3% bears against a seat35 provided at the top the recess 25a and it is secured to the handleby. means of a self-tapping screw 57-. The bracket is provided with avertical strengthenin rib 33b extending along its length, as shown.

The function of the forward ski-rt s'ect ion 25.. or" the handle is toconceal the front hand-1e sri-D- port 36; it is, as shown, in the formof an apron extending downwardly from the forward end of the handgrasping portion 25. This apron at its lower rear end 38 curves backover the top of the shell, as shown. The rear handle section 2! is.

provided with a similar apron 39 extending forwardly toward the apron38, as shown, and the space between the ends of the two aprons 38 and39-is, filled by means of a metallic plate 40. The plate 49 is formed ofa metal which is inherently resilient, and it is caused to resilientlyengage the two aprons 38 and 35, whereby it is secured to the handle;each apron preferably and as shown is provided with reduced endextensions 4!, while the baffle plate 40 is given a complementary shapein cross section whereby it may be snapped over the two reducedsections. To remove the plate, it is merely necessary to insert a' screwdriveror some other similar instrument underone side and pry it up tospring it away. When the plate is assembled, as shown in Fig. 1, its topsurface merges in a smooth line with the curved aprons.

The'handle and baiile plate structure just de-' scribed is described andclaimed in my Patent 2,443,448, assigned to the assignee of the instantapplication.

Thethermostatic control switch and its mounting in the fiatiron asdescribed below is the subject of my patent application, Serial No.165,216, filed concurrently herewith, and also a division of myapplication, Serial No. 676,909, now Patent N 0. 2,543,736.

The heatingelement is controlled by mean of, a thermostat 4-2 which isarranged to respond to the temperature of the soleplate so as to hold asubstantially constant temperature in the plate. This thermostatcomprises a supporting frame. having a U-shaped base plate. 43. The.bight of thebase is secured to the top surface of the sole; platehymeans of a pair of screw 43 a (Fig. 2) At the outer edges of the two,legs of the base plate are upright walls id-which extend rearwardly fromthe bight, across, the top of the soleplate. Preferably, the section ofthe soleplate under. these rearwardly extending walls i cored olut'so'asto form a cavity 45 (Fig. 1)

Secured under the bight of the base plate 43' is 'a bimetallictemperature responsive bar 46 formed of two metals having dissimilartemperature coefficients of expansion rigidly secured togetherlengthwise in any suitable way, as by welding. Preferably, and as shown,this bar will be formed of two reversed sections in order to minimizetemperature overshoot in the fashion described and claimed in the U. S.patent to R. A. Winborne No. 2,128,869, dated August 30, 1938. Thethermostat bar 4Bha its left-hand end, as viewed in Fig. 1, secured tothe base plate 43 and its opposite end extended over the cavity 45.Clamping the thermostat bar d tto the base plate 43 is a clamping blockformed of a material.

4 having a very good heat conductivity, such as aluminum. This block isprovided with :a central longitudinal channel-like passageway 48 inwhich the bimetal bar is mounted. forward part of this block is clampedbimetallic bar 25 :and to the base .plate ia by means or a rivet 19. Thethermostat bar i further secured to the base plate by a rivet 50 spacedrearwardly from the rivet 49, and which is not fastened in any way tothe block.

The thermostatic switch further comprises a switch having a contact 5|and a cooperating; contact 52. The contact 51 is mounted upon an.electrically conducting arm 53 formed of a relatively stiff springmaterial. This arm, at its: rear end, is rigidly secured by means of arivet. to and under atransverse section 58 of the sup-- porting framewhich joins the rear ends of the: upright walls of the base plate, andit is electrically insulated from this plate by suitable ma-- terialsuch as sheet mica. The contact 52 is mounted upon a switch arm 55,likewise made of f spring material, but which has not the spring;strength of the arm 53;. The arm 55 i supported; at the rear upon thetop of the plate section 54 by; means of a rivet and is electricallyinsulated from; the plate by mica. The two switch arms 53, and,& 55 arespaced apart transversely and are in; sub stantially parallel relation,but the forward end; of the arm 53 is provided with a lateral offset 56;extending to the arm 55 'so as to bring its. contact 5! into abuttingrelation with the contact 52:.

The switch arm 53 biases itscontact. 5!. up wardly, whereas the arm 55biases its contact 52 downwardly; but the switch arm 53,: bearsagainst.- an'adjustable stop- 560. so that the; contact 5li normally'isa fixed or'stationary contact; the contact 52 is the movable one and isoperated to open and close the switch responsively to the deflection ofthe bimetal bar 46, as, it heats and cools. The bar is constructed andarranged so that its free end moves upwardly as it heats up and movesdownwardly when it cools. Mounted On t s fr end of the bimetal bar is anupright switch actuator 51. This actuator is laterally positioned with.reference to the bimetal bar so that it lies directlyunder'the springarm 55. The actua or is in thetor-m of a tube'closed at it upperend andis mounted upon the upright arm of a right angle bracket 58, the otherarm of which is, secured in any suitable way to theend of;thethermostat, asby welding. The actuator 51 is formed of asuitablerefractory electrically insulatin material, and it is secured to thebracket 58 by means of a suitable cement.

The switch contacts 5| and 52 are connected in the iron heatingcircuit-to control its energi-v zation by opening and closing. When theiron is energized but .has not as yet been heated up, the top of theactuator 5! is spaced below switch, arm 55, as shown in Fig. 1. But whenthe thermo-- stat moves upwardly as; its temperature rises; it will movethe actuator upwardly to close this. space and engage the switch arm 55to move it; upwardly against its downward bias andthereby open thecontacts 5| and 52, whereas when the thermostat cools and deflectsdownwardly it per mits the switch arm 55 to'return the contact 52. tore-engage contact 5l and thereby reclose the switch;

In operation, therefore, the switch arms 53 and. 55 carry current forthe iron'heating element- These arms preferably'will be made ofstainless steel'or other suitable heat resisting alloy. 'Suclr materialswhich may be used at flatiron tempera-- amplitude.

" plate. This terminal 69 also is lated from the other two terminals andthe plate some heating of the springs due to the passage of current. Inthe case of spring 53, this is not too important, because it isrelatively thicker than spring 55 and its resistance, therefore, isless. However, in the case of spring 55, this is important, both becausewith its higher resistance it :tends to:heat to higher temperatures andbecause it may conduct heat to the thermal bar through the switchactuator '|.v This switch .arm, if heated too high, would act as anauxiliary booster heater for the thermostat bar, and cause it to operatewith too narrow a temperature To obviate this, I shunt the spring arm 55with a good heat conducting strip 59 which, as shown, overlies and isconnected at one end with the switch arm and terminal '65 by the rivetfastening these members together, and at its other end is fastenedbetween the other end of the switch arm and its contact 52. The shunt ismade of brass, aluminum or other suitable good electrical conductor. V

It will be remembered that the switch arm 53 holds the contact 5| in astationary position, and further that the spring arm 53 is stronger thanis the spring of the arm 55. ,The arm 53, however, is prevented frommoving upwardly by means of the aforementioned stop 5611, which is madeof electrically insulating material and is mounted within adjustingscrew 68 which, in turn, is threaded in one end of a lever 6|. Thislever intermediate its ends and at the sides is provided withdown-turned cars 62 which are journaled upon a transverse shaft 63 whichpasses'through theears .and the side walls 44 of the base plate andwhich has its ends pinched or squeezed, as shown in Fig. 2, to preventthe shaft from working loose. The end of the lever 6| opposite theadjusting screw 60 rests upon an adjusting cam 64 (claimed in thepresent application) by means of which the position of the lever andthereby the position of the stop screw 60 may be adjusted. Thisadjustment varies the position of the stop 56a and this varies thepositional relationship between the switch arm 53 and, consequently,thearm 55 and the actuator 51. This changes the temperature setting, ofthe control device.

As described more fully in my application Serial No. 676,909, the switch5|, 52 is electrically connected in series with the circuit of theheating resistance l3 of the heating element, and for this purpose thereis provided a terminal structure comprising a pair of rigid terminals 65and 66 of roughly L-shape having their horizontal legs mounted on thetop of the transverse plate 54 of the thermostat frame and their uprightlegs extended upwardly through an opening 61 in the top wall of theshell l9 and into a relatively large cavity 68 provided in the rearhandle section 21,

' as shown. The terminal 65 is electrically insu- 'lated from theplate-54 and from both switch arms 53 and 55, whereas the terminal '66,while it is electrically insulated from the plate 54 and the terminal65, is in electrical contact with the switch arm 55. The terminalstructure further comprises a third rigid terminal bar'69 which is theplate '54 and projects outthe rear of the shell from the electricallyinsumounted under wardly toward 54, but is in direct electricalengagement with the switch arm 53. The three terminals 65, 66, 69

' aresecured by means of the rivets which hold the two switch arms onthe plate 54.

The-terminals are adapted to be electrically .end of the depression 89.

electrically connected with the terminal |6 of the heating element. Theother terminal I! of the heating element is connected with the terminal69, which is in electrical engagement with the switch arm 53, by meansof a conductor 18 connected at one end to the terminal I! and at itsother end with the terminal 69 by means of a screw 19. The terminal 66,which is in electrical engagement with the switch arm 55, iselectrically connected with the other conductor of the supply cord bysuitable means.

In view of these connections, it will be observed that the switchcontacts 5| and 52 are electrically connected in series with the heatingelement resistance l3 and with the supply source so that when the switchcontacts are in engagement the heating element is energized, whereaswhen they are opened the heating element is deenergized. The thermostat46, in operating the switch contact 52 away from and to return intoengagement with contact 5| in response to rise and fall in temperature,operates to hold the desired temperature in the soleplate.

The thermostat switch mechanism and mounting just described is morefully described and claimed in my concurrently filed application, SerialNo. 165,216.

As has been explained previously, the temperature held in the soleplatemay be varied by varying the position of 'the contact 5| which Variesthe space between the switch actuator 51 and the switch arm 55 and thisis accomplished by changing the position of the abutment 56a; this, inturn, is accomplished by setting the cam 64, which varies the positionof the lever 6|. disc-like base plate 82 which is arranged to rotateupon a support 83 which is formed as an extension of the base plate 43of the support frame, this support 93 being positioned in elevatedrelation from the plate 43 by a vertically offset section 84. The part83 not only supports the cam, but it functions as a bearing for the cambase plate 82, and for this purpose it is provided with a plurality ofupright rounded bosses 85 which engage the under surface of the camplate. Superimposed upon and secured to the cam plate 82 is a circularcam member 86 shaped to define a cam rise 81 on its periphery. It issecured to the cam base plate in any suitable way, as by spot welding.At the center the cam member 86 is provided with a cone-shapeddepression 88 which extends downwardly through a central apertureprovided for it in the base plate 82; and the cam bearing 83 likewise isprovided with a cone-shaped depression 89 at the center. The cam 64 issecured to the extension 83 by means of a spring 90 which is formedintegrally with the cam base 82 and extends outwardly from one edgethereof and, thence, is folded thereunder, as shown in Fig. 1. On theend of the spring 90 there is formed a lip 9| and also an aperture whichis received by an extrusion 92 formed on the frame at the lower Toassemble thecam with the extension 83, the assembly of the cam andspring is slipped over one edge of the ex- The cam 64 comprises acircularv tension and the spring snapped over the extrusion with theaperture in its end receiving the extrusion. The lip helps to snap thespring over the extrusion. The action of the spring 90 holds the camplate 02 against the protuberances 05 upon which it rides.

The cam 60 is rotated by means of a rod 93 which is verticallypositioned in the forward end of the iron, and which extends upwardlyfrom the cam structure through openings 90 and 95 provided for it in thetop wall of the shell and inthe baffle plate 3i, respectively, andthence extends upwardly into the recess 26a provided by the skirt 26 atthe forward end of handle 25. At its lower end, this shaft is providedwith a pair of keys 96 positioned on opposite. sides of the shaft andwhich preferably will be formed by squeezing or pinching out sections ofthe shaft.

These keys are arranged to operate in complementary slots 01 provided inthe cam plate 86. They alsovfunction to ride upon the top surface of thebottom wall of the conical depression 89 in the support 83 and therebysupport the shaft in its vertical position.

As described and claimed more fully in my aforesaid application, SerialNo. 676,909, at the top of the shaft 93 there is a pair of oppositelypositioned keys 98 similar to the keys 90 and preferably arranged in thesame angular relation with reference tothe shaft as are the keys 96. Thekeys 93 at the top of the shaft effect a driving connection with anoperating lever 99 which is positioned at right angles to the shaft andwhich extends outwardly through the front wall of the recess 25a, thewall being provided with an elongated transverse slot I for thispurpose. The lever 99 on its inner end is provided with an upwardlyextending inverted cup-shaped protuberance II]! which is provided in itsupper wall with slots (not shown, but similar to slots 91) and whichreceive the keys 98 to effect a driving connection between the lever andthe shaft. Thus, when the lever 03 is operated transversely in the slotI00, the shaft 93 is rotated in order to adjust the cam.

The upper end of the shaft 93 is journaled in a bearing provided for itin an extension I02 provided on the forward end of the upper arm 35 ofthe handle support 30.

On the forward end of the lever 99 which projects from the slot 00,there is attached an operating knob I03.

Also mounted within slot I00 is a temperature indication plate I04 whichis roughly semi-circular in shape and which is so constructed andarranged that when it is inserted in the slot I00 a peripheral portion I05 thereof is exposed to view, and upon this exposed portion there aresuitable indications for soleplate temperature settings for ironingvarious materials, such as rayon, silk, wool, cotton and linen. Also, ithas an indication for off, in which position of the lever 99 the cam isso positioned that it moves the contact 5I downwardly so far that itleaves the contact 52 which will be held in an upper open position bythe actuator 51. The cam rise surface 81 gradually rises from a hightemperature setting position corresponding to linen to a low temperatureposition corresponding to rayon and then has an abrupt rise I0'5a whichis the o position; in this position of the cam, the lever GI is operatedto depress the abutment 500. so far downwardly that switch arm 53separates its contact 5| from contact 52, which latter contact issupported by the actuator .8 51 on the thermostat. As the cam is rotatedfrom the off position, it first. permits the arm 53 to rise to reclosethe contacts. and, thence, as it continues to move, increases the spacebetween actuator 51 and switch arm 55, and thereby increases thetemperature setting. Upright ears I052) and I050 function to limitmotion of cam 86 in assembly and insure proper positioning of the cam.

The indicator plate I04 is provided with a circular opening I06 whichreceives the upwardly extending boss I0! of the lever 99, and aroundthis boss and sandwiched between the lever 99 and the plate I04 is acup-shaped spring I01 which biases the two members apart and which holdsthem firmly in the iron assembly by forcing them against the upper andlower walls of theslot lliflrespectively.

It will be understood that to assemble the shaft 93, the lever '99 andthe indicating plate I04 with their associated parts, first the shell ISwith the handle attached will be separated from the soleplate, then thelever 99 will be assembled with the spring I01 and with the temperatureplate I04 in their proper relative positions shown in Fig. 1. Thisassembly will then be inserted into the'slot I00. Then the shaft 93 willbe inserted through the chamber 26a so that its upper end passes throughtheapertures in the lever and indicating plate and so that its keys 93are received in the slots provided for them in the protuberance IOI. Theshaft, of course, is forced inwardly until its upper end is received inthe opening provided for it in the bracket extension I02. Preferably,means will be provided for holding the shaft up in its assembledposition. This means comprises a spring member I010. of roughly U-shapepositioned under and against the lower surface of the top wall of theshell. The legs of this member straddle the shaft 93, and at the outeredge of the bight of the U there is an upwardly and outwardly offsettongue I0Ib which has its top outwardly extending part overlying the topwall of the shell. Formed on the inner edge of the bight between the twolegs is an upright flexible spring arm I 010 which bears against theshaft and holds it in place. The spring also functions to preventrattling of the shaft when the iron is in use. After the shaft isassembled, as, described, and the spring I0'Ia applied, the handle andshell are moved into assembled relation with the soleplate, while thelower end of the rod 93 is moved into the conical protuberance 88 of cam86 which guides it to the central slots 9'! therein, and, thence, intothe conical projection '89 of frame 03 which guides it to its centralaperture. If, when the shell is assembled, the keys 9% do not registerwith the slots 91, the knob 503 will be moved back and forth until theydo; and When they do the shell may be lowered in position on thesoleplate, and then secured by the screws 200.. After this, the coverplate 40 may be snapped in place to cover the screws.

While the knob I03 is used by the operator to adjust the. temperaturesetting, at times it may be desired tochange the basic calibration ofthe thermostat. This may be done readily by adjusting the screw 60 inwhich the insulator 56a is supported. This may be done convenientlythrough an opening I09 provided in the top wall of the shell I9immediately above the screw and through which a suitable instrument,such asa screwdriver may be inserted to set the screw.

It will be observed that the screw 60 is accessible when the plate 40 isremoved. Preferably, a spring H will be provided to hold the screw 60 inany position in which it is adjusted.

Suitable signal means are provided for indicating when the thermostat isclosed and when it is opened. This means comprises a gas glow lamp II Ilocated within the chamber 68 of the rear handle section 21. 'This lampis mounted in a U-shaped bracket H2 having a base H3 at the bottomsupporting the base of the lamp, and a pair of prongs I M at the topresiliently engaging and holding the other end of the lamp. The bracketH2 is attached to the terminal 66 by means of a rivet H5. One terminalof the lamp is electrically connected with the terminal 66 and therebyto the supply conductor by being clamped between the terminal and thebracket. The other terminal of the lamp is connected with the terminal69 through a current limiting resistance IIB. In view of thisarrangement, it will be observed that when the switch is closed the lampwill be short-circuited and thereby be de-energized whereas when theswitch is open the lamp will be connected in series with heater l3 andacross the supply source and thereby energized to light. The lamp isviewed through a window or opening (not shown) located in the side wallof the chamber 68 opposite the lamp.

While I have shown and described a particular embodiment of myinvention, it will be obvious to those skilled in the art that variouschanges and modifications may be made without departing from myinvention in its broader aspects and I, therefore, aim in the appendedclaims to cover all such changes and modifications as fall within thetrue spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In an adjustable cam structure a bearing plate having on one side abearing surface provided with an opening therein, said plate having acylindrical protuberance on the other side extending from said opening,a cam mounted on said bearing surface for rotation thereon, a springretaining element attached thereto and directed about the edge of saidplate to said other side where it rotatably engages said protuberance toretain said cam in engagement with said bearing surface. 7 y

2. In an adjustable cam structure, a bearing plate having on one side abearing surface provided with a central opening therein and a pluralityof circumferentially spaced upright bearing bosses thereon, said platehaving on its other side a cylindrical protuberance extending outwardlyfrom around said opening, said cam resting on said plurality of bossesfor rotation thereon on the axis of said opening, and a U-shaped springarm attached to said cam and passed over the peripheral edge of saidplate to said other side where it rotatably engages said protuberance tohold said cam on said plate.

3. In a cam structure, a horizontal plate having an opening from whichdepends an inwardly tapered protuberance having therein a centralcircular aperture, a horizontal cam rotatable on the upper surface ofsaid plate in the axis of said opening, said cam having an inwardlytapered protuberance having a central circular opening, a vertical shaftfor operating said cam having its lower end directed through both saidcentral circular openings, said lower end having thereon a key whichbears against said first-named protuberance to support said shaft andwhich key is received in a slot provided for it in said secondnamedprotuberance to eifect a driving connection between said cam and shaft.

4. In a cam structure, a horizontal plate having an opening from whichdepends an inwardly tapered protuberance having therein a centralcircular aperture, a horizontal cam rotatably mounted on the uppersurface of said plate in the axis of said opening, a cam havinganinwardly tapered protuberance having a central circular opening, avertical shaft for operating said cam having its lower end directedthrough both said central openings, said lower end having thereon a keywhich bears against said first-named protuberance to support said shaftand which key is received in a slot provided for it in said secondnamedprotuberance to effect a driving connection between said cam and shaft,and a U-shaped spring retaining member having one arm attached to saidcam and the other arm rotatably engaging the under side of said platefor holding the cam in position on the plate.

FRANK E. FINLAYSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

